In the abovementioned motorization systems, elements, for example fittings, are typically set in motion relative to one another around hinges. These systems thus comprise lines of hinges that generally use motorization components of the torsion spring, spiral spring or Carpentier joint type, making it possible to counter the resisting torques and to guarantee the necessary margins in terms of torques generated in order to ensure the complete deployment of the appendages.
In this context, the known motorization components exhibit a changing or variable motorization torque involving an over-motorization which brings about shocks at the end of deployment.
These shocks can be significant and can generate damage to the space appendages at the end of deployment, as well as stray torques damaging to the piloting of the spacecraft. To mitigate this problem, the deployable structures can be dimensioned and reinforced so as to be able to withstand the end-of-travel shocks generated in deployment, but this solution is unsatisfactory and notably results in an increased weight for the complete structure.
Some lines of development have led to the devising of deployment mechanisms with almost zero resistive torque. Such mechanisms, such as the line of hinges described in the patent application FR 2635077, offer the advantage of requiring only little motorization power and generate minimized end-of-travel shocks. Other mechanisms are borne out of enhancements made to the above mechanism, notably in terms of weight and volume. Such a deployment mechanism is disclosed in the patent application FR 0605653.
The known mechanisms, such as those described in the abovementioned patent applications FR 2635077 and FR 0605653, have an angular deployment capability that is limited to 180°. Moreover, their overall kinematics, because of their structure, generate very irregular motorization torques. Finally, the speed of deployment of the known deployment mechanisms, as already stated, results in a restoration of energy at the end of travel, therefore a shock, because said speed of deployment is not regulated.
To correct these drawbacks, a motorization device has been proposed with control torque, described in the patent application published under the reference FR 2968234. Such a device makes it possible to have an almost zero resisting torque, and is based on the use of rolling flexible tracks that already exist in the system to produce the motorization. A specific form is given to the flexible tracks so as to allow for an offsetting of the point of contact between the flexible tracks relative to the crossover point of winding means such as wound flexible blades or even cables, forming a link element between two substantially parallel winding cylinders forming fittings with the flexible tracks, to which different components of the system are linked. In this way, a torque dependent on the distance between the abovementioned point of contact and crossover point provokes the mutual rotation of the flexible tracks, and thus the mutual rotation of the fittings. The “crossover point” between the link element-forming winding means should be understood in the wider sense to be the axis substantially parallel to the longitudinal axes or axes of revolution of the fittings, passing at the same time through the two winding means.
In the abovementioned device, a problem may arise when foreign bodies come to be housed between the rolling flexible tracks, possibly resulting in a total jamming of the hinge. The foreign bodies may originate from the space surrounding the device, or else from the device itself, the foreign bodies then possibly being parts of the system that have accidentally become isolated or even residues of matter originating from part erosion phenomena, for example.